This is a very useful perk as it allows players to successfully take out or avoid enemy explosives before the explosives can kill teammates or themselves. It is more effective on game modes where a well placed explosive can guarantee a team's defeat (such as Search and Destroy), but less effective in "run and gun" game modes (such as Team Deathmatch), as explosives are somewhat less important in these modes. It is unpopular with players because the other first tier perks are useful in more game modes, and because an observant player will easily avoid enemy explosives without the perk. This perk can be combined with the third tier perk Deep Impact to shoot enemy explosives through walls. One often overlooked benefit of this perk is that it shows where enemies are or where they have been. Many players will use Bomb Squad for a counter sniping class to hunt down and take out enemy snipers before they can do much. Since snipers will almost always use Claymores, this is highly advised for this class. However, Bomb Squad only works against opposing factions, so in Team Deathmatch, players do not see explosives placed by players who are in the same faction.
The World at War version is a lot more useful than the Call of Duty 4 version, because while claymores have very visible red laser lines, Bouncing Betties are very hard to spot. This perk is a must due to the extremely small size of the Bouncing Betties. If you come across one and you have the perk activated, it is easy to quickly destroy it and move on into attacking the enemy. In Hardcore playlists, Betties are also extremely common, especially in medium-large sized map, which is where the perk shines brightest. This perk is also extremely useful in Search and Destroy & Sabotage matches, as Betties and Satchel Charges will often be planted around the objectives and will be quickly detonated if not taken out. If a player has the perk on, that player can come and destroy the explosives, giving enough time for others to plant the bomb and take their defensive positions for a safe victory.
In maps without tanks, such as in the Map Pack 1, Map Pack 2, and Map Pack 3 playlists, Bomb Squad is probably the most useful perk 1 there is, as due to the lack of tanks people use Bouncing Betties a lot, so you will be easily protected from them. Flak Jacket can also help, but it is a tier 2 perk.